Oh yes. Project Brian. Madder than a box of frogs on acid. A "minimum change" T23 that just had a different hullform, a completely different propulsion system, no change to accommodation or safety standards and a bunch of weapons that had in no way been designed for the naval environment. Which was obviously going to cost "about the same" as a T23. What could possibly go wrong?
If you know anything about T45, you'll realise that it ain't a happy place right now - primarily for propulsion reasons. The old arguments against it as an ASW variant remain valid - you'd need to change most of the marine systems and you'd need to rearrange the internals, all of which make it a "new" ship in terms of drawings required and production effort. The only thing you might save on is some hydrodynamics tests, which tend to be comparatively cheap in any case. Certainly not a game changer in per ship cost.
T26 is eminently capable of being fixed. All it requires is the will to allow people to address the known problems (ie change the bits of the design that are causing the issues) and a hard-headed negotiation with BAES and HMT to get where the ship cost ought to be. That means being open and honest (internally) about what's wrong and ending the game of chicken.